The present invention is generally directed to processes for the preparation of ink compositions and ink jet printing methods thereof. More specifically, the present invention relates to processes which provide sterically and/or electrostatically stabilized colorant, especially pigment particles suitable for use in electrophotographic imaging and ink jet printing methods. In embodiments, the present invention relates to processes for the preparation of highly stable colorant dispersions, such as pigment dispersions selected for ink jet inks, and wherein the dispersions can be prepared at high temperatures, for example at about equal to or above 100.degree. C., with microfluidization. The present invention also relates to polymerization processes for preparing stabilized resin particles that possess narrow molecular weight distributions or polydispersity (M.sub.w /M.sub.n) properties and narrow particle size distributions, and which polymerization processes can be accomplished with high monomer to polymer conversion. In embodiments, the present invention relates to polymerization processes that directly yield stabilized resin particles with resin number average molecular weights (M.sub.n) equal to or above about 2,000 to about 500,000, and with a resin polydispersity ratio of the weight average molecular weight (M.sub.w) to the number average molecular weight (M.sub.n) of from about 1.0 to about 2.0, and preferably from about 1.1 to about 1.5. Stabilized refers, for example, to electrostatic and/or steric solid-liquid or colloidal dispersion phenomena. The stabilized resin particles and stabilized colorant, such as pigment particles that can be formed by in situ monomer polymerization reactions and colorant, such as pigment coupling reactions, respectively, in embodiments, may be used directly in selected liquid ink imaging processes without the need for further processing steps, such as isolation, purification, classification, and the like. In other embodiments, the present invention provides processes for preparing stabilized colorant, such as pigment particles. The present invention also provides, in embodiments, a pseudoliving polymerization process that enables the direct preparation of narrow polydispersity homopolymeric and copolymeric reactive emulsifiers, or stabilizers which may be selected to prepare stabilized resin particles directly from monomers, and stabilized colorant particles.
In embodiments, first formed intermediate polymers, referred to as stabilizer compounds or reactive emulsifiers, are of the formula (I-A-B)-SFR where I is a free radical initiator molecular segment, or fragment, A is a polymeric segment, and B is a polymeric segment, and which A and B segments can be similar, or dissimilar in composition and physical properties, and SFR represents a covalently bonded and thermally labile latent stable free radical functional group. The intermediate polymers may be optionally isolated and stored indefinitely at ambient temperature, that is about 25.degree. C., or at room temperature, about 25 to about 35.degree. C., or reacted directly, or in situ, with additional monomer or monomers to form stabilized resin or colorant particles. The processes of the present invention can, in embodiments, select known free radical initiators in combination with, for example, an oxygenated stable free radical agent, and a free radical reactive, polymerizable, monomer or monomers to enable stabilized, narrow polydispersity, homo and copolymeric resin particles. The aforementioned resin formation and stabilization processes can optionally incorporate a colorant into the reaction mixture before, during, or after polymerization to primarily provide particle coloration capability. In an alternative embodiment the stabilized colorant, such as pigment particles may be added to the aforementioned stabilized resin particle formation process to provide enhanced pigment dispersion and excellent stability properties to the resulting pigmented resin particles or toner particles. Enhanced colorant, such as pigment dispersion, and excellent resin particle stability imparts desirable image quality characteristics to electrophotographic and liquid ink impressions and transparencies, particularly for color images, for example high fidelity color reproduction and transparency projection efficiencies. Images generated with the ink compositions obtained with the processes of the present invention in embodiments thereof are sharp, waterfast, lightfast, and of high optical density, exhibiting substantially no, or minimal feathering, and moreover, the inks can be electrically conductive.